algebraic datatypes

[Ronald Legere]

I would like to define something like
the scheme 'define-datatype' macro (from Essentials of programming languages
2) in python.

Essentially,
datatype Tree = Node Tree Tree | Leaf Int
should translate into a class structure like this:

#class Tree
# abstract

class Node:
    def __init__ (self, atree,atree)
              self.r = atree
              self.l = atree
# and some accessors etc...

class Leaf:
      def __init__ (self,anint)
               self.aninit = aninit
# AND so on....


Is this something that I can do? Should I use the parser library and make a
preprocessor? Is this to hard to do that way? Is there an easier way?? Am I
missing something?

Cheers!